10 of the World's Most Prolific Serial Killers

Green River Killer Gary Leon Ridgway cries as he reads a statement in court, Dec. 18, 2003, in Seattle. Ridgway received 48 life sentences, without the possibility of parole, for killing 48 women. Elaine Thompson-Pool/Getty Images

In the 1980s and 1990s, investigators struggled to catch the infamous "Green River Killer," who preyed upon prostitutes and teenage runaways in King County in Washington state. The killer would strangle his victims while having sex with them, and then dump their bodies in remote areas near the Green River.

Police suspected a truck-body painter named Gary Ridgway for years, but they couldn't make a case against him until DNA advances enabled them to link him to some of the victims in 2001. To avoid the death penalty, Ridgway confessed to 48 of the murders in 2003, and received multiple life sentences. In 2011, a 49th body was found, and linked to Ridgway, who received yet another life sentence.

Since then, Ridgway has confessed to many additional killings. ABC News reported in 2013 that he claimed a body count of close to 80. He claimed that he had found religion and wanted to bring closure to the victims' families. Charlie Harger, a radio journalist who interviewed him and was skeptical of his claims, said he believed that Ridgway actually was out to impress people that he was superior to the more famous serial killer Ted Bundy [source: Dolak].